Building a new pc.

[Barkles]

I use AMD and they more than often work completly fine with games, if anything sometimes better. When Watch Dogs came out a lot of Nvidia users couldn't even get above 10FPS, whereas most AMD users were fine, including myself.
It all depends what you want, I wouldn't go around slagging off AMD, they are pretty good.

there are plusses and minuses to both
personally I use an i5 4670k w/Nivdia Gtx760 because of the overclocking abilities plus the reliability, and personally i can get a solid sixty on max settings for most games I play, or at least on high, watch dogs included.
A lot of AMD CPUs are widely reagrded as less powerful than those of intel, there is a reason for this, but Im not smart enough to know. 
As for AMD GPUs I think theyre great and work well, although I prefer Nvidia cards.
My advice is depending  on your budget, dont skimp on last gen products for your rig, especially CPU and GPU becuase they will most liekly be the things you'll keep longest, aside from the case.
for  sub £500 builds go for a AMD Fx with a R290 and thatll work well
for above that go for a i5 4690K with a Gtx 970, theyre some of the best on the market at the moment and im hoping to buy a 970 when I can

I hope that helps a little, im not very sure about lots of techical stuff but there is lots of sites that can help yuo with that